This invention relates to a rollover bar for a motor vehicle, particularly for a convertible, which comprises several mutually connected frame parts and is fastened on its laterally exterior lower ends to the stationary vehicle body.
From German Patent Document DE-GM 85 23 831, a convertible is known in which a rollover bar is arranged behind the front seats.
This rollover bar comprises two inversely U-shaped frame parts which are arranged behind the seats and which are fastened in the same plane situated at a distance side by side to a horizontal frame part.
In addition, this rollover bar comprises rear frame parts which act as supporting arms and which are fixedly connected with welded-on bushes of the U-shaped frame parts.
All frame parts of this rollover bar are formed by linear or bent steel tubes of a circular cross-section, each frame part having a constant cross-section along its whole longitudinal dimension.
This rollover bar has the disadvantage that the dimensioning of the tube cross-section of the frame parts must be adapted to the highest occurring stress so that the rollover bar is overdimensioned at least in partial areas, requires a lot of space and has a high weight because of the steel construction.
In addition, the weld seams between the horizontal frame part and the two U-shaped frame parts must alone transmit the occurring forces.
It is an object of the invention to further develop a rollover bar of the initially mentioned type in such a manner that, while its function is good, it can be manufactured in a simple manner and at reasonable cost, requires minimal mounting space, and has a low weight.
According to the invention, this object is achieved by providing a rollover bar arrangement comprising internal-high-pressure-formed frame parts.
Principal advantages achieved by means of the invention are that, by using internal-high-pressure-formed frame parts for the rollover bar, a rollover bar is provided whose changeable cross-sections are adapted to the occurring stresses and which therefore requires a minimal mounting space.
The internal-high-pressure-formed frame parts can be manufactured in a simple and low-cost manner. Because of the plug-type connections between adjacent frame parts, this rollover bar can withstand extreme stress. In addition, the bending stress in the weld seam is reduced by means of the plug-type connections which increases the safety of the component. As a result of the high-pressure deforming, the structure of the material will change and the component strength and the torsional stiffness will increase.
Any desired shape of the frame parts can be implemented and the space conditions are utilized to an optimal extent. Add-on parts can easily be integrated in the rollover bar because of the internal-high-pressure deforming.
The internal-high-pressure-formed frame parts have a high precision with respect to their shape and measurements so that their assembly is simple.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.